The structure of convection currents was experimentally studied in the model system layered intrusion–feeding conduit–parental magma chamber. Persistent hydrodynamical and thermophysical interaction between interrelated melts of the parental magma and intrusive body occurs through the feeding conduit. Being associated, they control the structure of convection currents and mechanisms of heat and mass transfer in the intrusive, conduit, and magma chamber. The existence of two convection countercurrents in the conduit has experimentally been established: inner central lifting jet and outer annular downward current along the conduit walls. At the top of the conduit, the downward current has the lowest temperature and appears to be quite in equilibrium with the earlier precipitated crystals. Moving downward along the conduit wall, the annular descending current interacts with the lifting jet and, as a result, becomes hotter and undersaturated relative to the crystals that formed before. Thus, there is no possibility for heterogeneous crystallization to occur on the walls of conduit. The experimentally simulated mechanism of melt interaction in a whole natural system rules out the possibility of formation of a zone of immobile melt with stable steady-state temperature stratification anywhere in the chamber’s volume.